Known is a collision energy absorber attached to a front portion of a carbody of a railcar and configured to absorb collision energy to protect crews and passengers when, for example, railcars collide head-on with each other or a railcar collides with an obstacle. Such energy absorber is typically constituted by a hollow columnar member made of metal and is provided such that an axial direction of the energy absorber coincides with a forward/rearward direction of the carbody. With this, when the collision energy absorber collides with the obstacle, the collision energy absorber gradually buckles in the axial direction to deform in an accordion shape. Thus, the collision energy absorber absorbs the collision energy to reduce an impact transmitted to the carbody.
The collision energy to be absorbed at the time of the collision of the railcar is extremely larger than the collision energy to be absorbed at the time of the collision of an automobile or the like. Therefore, a capacity of the collision energy absorber needs to be increased. However, just increasing the capacity causes a significant weight increase. Therefore, in recent years, collision energy absorbers made of fiber-reinforced resin have been proposed to satisfy a requirement of weight reduction (see PTL 1, for example). The amount of energy absorption per unit weight of such collision energy absorber made of fiber-reinforced resin can be made larger than the amount of energy absorption per unit weight of the conventional collision energy absorber made of metal. Thus, the weight reduction is realized.